Normal map baking does not reflect details
When baking a normal map from highpoly mesh to lowpoly, several conditions have to be taken into account (assuming lowpoly is already unwrapped):


Highpoly must be selected first, lowpoly - last. So lowpoly should be active, i.e. selected last. Also they have to be in the same place in 3D space.
Lowpoly must have image to be baked to. If Blender Internal, It's simply a matter of assigning image in UV/Image Editor while mesh in Edit mode (or by using a material). If Cycles, Image node with this image should be selected in Node Editor.
In Render Bake settings, Selected To Active has to be checked. 



This will make Blender to bake the normals from the secondary selection to the primary selection in 3D Viewport. 



Also read:


Baking normal maps from highpoly to lowpoly
Bake normal maps 
Baking Normal maps in Blender Internal | Baking Normal maps in Cycles